There isn’t a single reason why the New England Patriots should lose to the San Francisco 49ers in their Week 11 matchup Sunday.

The 49ers rank dead last in total defense and 29th in total offense, and they’re allowing the most points per game in the NFL while scoring the 12th least. They’re 1-8, on their second starting quarterback, have an eight-game losing streak and an abohorrent roster.

So, needless to say things are not going well for Chip Kelly and the 49ers this season.

We usually discuss keys to victory in our game preview, but this will serve as keys to subsiding the overriding panic setting in among Patriots fans over the team’s struggling defense. Listing keys to victory would read like simplified John Madden-speak.

DON’T LOSE
We briefly went over the reasons why the 7-2 Patriots should win, but they proved last year they can lose to a Kelly-coached team in what should be a sure-thing victory.

The Patriots could lose if they once again make mistakes. They lost to the Philadelphia Eagles in 2015 because of a punt return for a touchdown, a blocked punt for a touchdown and a pick-six. Something similar would have to happen Sunday, and if they lose, even without tight end Rob Gronkowski and wide receiver Chris Hogan, the panic will be very, very real in New England.

GENERATE PASS RUSH
This is tricky, because Colin Kaepernick is another scrambling quarterback, but he struggles under pressure. The Patriots have to figure out a way to contain running quarterbacks while still bringing a semblance of a pass rush.

They improved against Russell Wilson in Week 10, sacking the Seattle Seahawks quarterback three times, but they could do better.

The Patriots might not have Jabaal Sheard, who began the season as a starter, against the 49ers. He posted on Instagram from the Boston Celtics game while the rest of the Patriots were in the middle of flying to California. Usually it would be assumed something was up and either someone else had a hold of Sheard’s account or that he would be arriving on a later flight, but the pass rusher’s snaps have been tumbling in recent weeks. He averaged 73 percent of snaps per game in the first six weeks and just 47.8 percent in the last three games. He played 16 snaps against the Seahawks.

Because of the lack of snaps, it wouldn’t be crazy to think he could be a healthy scratch. If he is, Rob Ninkovich, Chris Long, Trey Flowers, Shea McClellin, Geneo Grissom and Kyle Van Noy would be left on the edge. Dont’a Hightower and Barkevious Mingo also have pass rushing experience.

SEE CONSISTENCY FROM CORNERBACKS
It would be helpful if the Patriots figured out who are their second and third best cornerbacks relatively soon. Logan Ryan, Eric Rowe and Justin Coleman have received snaps in the roles. The Patriots also could turn to rookie Cyrus Jones.

Ryan and Jones (in a limited sample size) have struggled in coverage while Rowe and Coleman have been penalty prone. The Patriots have seven games to figure out who they want to play with No. 1 cornerback Malcolm Butler in the playoffs.

Ryan was graded by Pro Football Focus as one of the NFL’s best cornerbacks in 2015. Rowe has high upside because of his height, length and speed. Coleman is the best fit for the slot, and the Patriots thought highly enough of Jones to take him with their first selection in the 2016 NFL Draft.